A GENOME-WIDE SEARCH FOR WILD-SPECIES ALLELES THAT INCREASE HORTICULTURAL YIELD OF PROCESSING TOMATOES

To identify QTLs associated with horticultural yield it is necessary t o conduct replicated plot trials of the tested genotypes. The first st ep in the utilization of an introgression-line (IL) population of Lyco persicon pennellii in a processing-tomato variety (M82) for mapping su ch QTLs was to screen 51 ILs in a non-replicated plot trial. The resul ts of this survey were compared to those obtained in a replicated tria l of the same genotypes grown as single plants at wide spacing. Fruit characteristics were similar between the two stands, but yield was gen erally different. Eight lines that outperformed the control in the plo t survey were subjected to detailed analysis in the following year. Th e effects of these introgressions, measured on single plants, were rep roducible relative to the previous year's results. In a replicated plo t trial of these ILs and their hybrids involving two genetic backgroun ds, the product of yield and total soluble solids (horticultural yield ) in seven of the eight hybrids was 7-13% higher than that of their ne arly isogenic controls. The results revealed a consistent trend in the interaction between introgression effects and genetic background. Com bining the two introgressions with the largest contribution to horticu ltural yield in plots resulted in a 20% increase relative to the contr ol in the third year. This research highlights the potential of wild g erm plasm for yield improvement and the ability of nearly isogenic pop ulations to achieve this goal.